(1) Field of the Invention
This invention relates to the lubrication of aluminum and aluminum alloy surfaces during cold forming operations, such as cold rolling, and to rolling oil compositions suitable for such use. More particularly, this invention relates to improved rolling oil lubricant compositions having superior loadbearing (EP) properties which produce smooth uniform sheets free of surface defects, and which are non-staining and form a protective barrier on the surface of the metal.
(2) Description of the Prior Art
Lubricants are typically employed in cold forming processes to prevent damge to the surface of the metal and to generally facilitate the operation. It has been the general practice when cold rolling aluminum to apply a light petroleum-based oil, such as mineral oil, containing a small amount of an additive. These impart a number of desirable properties to the rolling oil but their primary function is to insure that sheets of uniform thickness and free from objectionable surface defects are obtained. A wide variety of lubricant compositions have been developed for this purpose but many of these formulations stain the metal immediately upon application or during the annealing operation. It would be highly advantageous, therefore, if rolling oil compositions were available for use with aluminum and aluminum alloys which exhibit excellent lubrication properties and do not produce undesirable surface stain.